— 45 — 



from which the surfaces above and below diverge at a right angle. 

 Fourth whorl ornamented with about forty fine sharp riblets, strongly 

 curved to the left, above the carina, and giving it a serrate edge, then 

 passing down to the next suture. On the sixth Avhorl they are crossed 

 by two revolving riblets below the carina, and on the seventh or body- 

 whorl these increase to fifteen or more, with many intermediate smaller 

 ones, which finally entirely efface the vertical lines. Mouth triangular, 

 simple, inner edge of outer lip crenately notched, thin; (columella and 

 canal lost). Length, 1.16 inch (or more); breadth, 0.70; mouth, 0.50 

 long, about 0.35 wide. The backward curve of the growth lines above 

 the carina suggests a Pleurotomoid shell, which is partly confirmed by 

 the curve forward of the posterior margin of outer lip remaining, but 

 the general form is so similar to that of Gabb's Potamides diadema, 

 that I have placed it in that genus until better known. (See Pal. of 

 Cal., I, p. 130, pi. 20.) Resembles Pleurotoma {Perrona) spirata Lamk. 

 Marysville Buttes, one specimen from Cret. B, Mr. Watts. 



Fusus supraplanus n. sp. (PI. II, Fig. 31.) 



Slender, whorls ten, rounded, regularly tapering to an acute point; 

 the ninth with five revolving ribs, deeply separated by narrow grooves; 

 upper fourth of whorl smooth, and slightly concave-tabulate; body- 

 whorl over half of length, with ten revolving ribs, and tabulated above; 

 * canal as long as body-whorl, straight, acute. The matrix of the seven 

 upper whorls shows traces of obliquely vertical embossed sculpture, 

 forming about twelve knobs on the seventh. Some traces of them are 

 also preserved on another specimen retaining more of the shell, from 

 which the sculpture of the body-whorl is also taken. Mouth imperfect. 

 Length (of figured one), 1.15 inch; breadth, 0.32; canal, 0.28. Nearest 

 to F. jlexuosus Gabb, with more and narrower whorls, straight canal, and 

 difterent sculpture. Many casts occurred in the Rose Canon bed, but 

 none quite perfect. The best as to surface characters, but with only 

 four whorls, must have been twice as large as that figured. Mr. Fair- 

 banks also found some in the False Bay bed, San Diego. Cret. B. 



Mitra simplicissima n. sp. (PI. Ill, Fig. 41.) 



Shell fusiform, whorls six or seven; body-whorl about equal to 

 spire, sutures lightly impressed; surface shining, with very faint 

 revolving strife, stronger toward the canal. Mouth narrow, acute 

 above, with three or more strong columellar folds near its middle. 

 (The one figured is broken, but a smaller one gives a dorsal view of 

 the anterior end.) Canal slightly twisted. Length, about 0.60 inch; 

 breadth, 0.25. No traces of larger specimens occurred, yet they may 

 be expected to be found, as the species is scarcely distinguishable from 

 the young of M. maura, a common species living in the same region, 



